For the next lesson the class will need some facts about galaxies and if possible an actual night time viewing of our Milky Way Galaxy. This will make a big difference in the understanding of this next project and the scale of the Galaxy. The information at the least should include the fact that everything seen with the naked eye (with the exception of the Andromeda Galaxy and the Large and Small Magellanic Clouds) is in our Milky Way, and that all the
individual
stars we see are only in our 10% of the Galaxy. Also some data and pictorials about the basic layout of a spiral galaxy.
Depending on the class, the concept of light years could be given so that they can get an idea of the vast size of the Milky Way (100,000 light years in diameter). From the last lesson on the size of our solar system, they may get a feel for the distance of a light year if it is explained that it takes approximately eight minutes and twenty seconds for the light of the Sun to reach the Earth and almost 5 1/2 hours for the Sun’s light to reach Pluto. This topic alone can take up many different directions. For our minimum purposes about sizes they should know the facts on
Handout B.
Before the jump is made to the large size of the Milky Way Galaxy, the students should be taken from the Solar System scale in gradual steps, otherwise they will not get a clear picture of the basic framework of the Galaxy. Inform them that the closest star is a little over 3 light years away and that there are about 100 stars within approximately 100 light years. If we could reduce our Solar System to the size of a 1/2 dollar, the closest 3 stars would be the size of periods on this page and spread out over one city block. This should be done with the class, take a 1/2 dollar and three students holding periods cut from a newspaper and walk out the length of one city block.
The next scale model will be the Milky Way Galaxy. I would suggest using 1 foot to equal approximately 15,000 light years of the Galaxy as a convenient scale. Explain to the students that the real Galaxy is so large that even though there are billions of stars in it, there is still so much empty space. They will need:
Material
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5, 1/4 inch thick 12 foot long cold rolled steel rods (can be acquired from a steel fabrication shop)
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tie wire
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8, 2 inch Styrofoam balls
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small pulley
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spool of 28 gauge wire (preferably black in color)
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can of spray adhesive
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large bag of iridescent flakes (an art supply store item, or can be cut on the school paper cutter from iridescent wrapping paper purchased at a card shop)
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large size silver glitter and star shaped glitter
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newspapers
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nylon string to hang model while working on it
Tools
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pair of wire cutters
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pair of pliers
